1. Field of the Invention
The present invention relates to a display driving signal processor for executing signal processing for displaying an image based on a video signal on an image displaying portion, and a method for use therein. Also, the invention relates to a display apparatus including such a display driving signal processor for displaying thereon an image.
2. Description of the Related Art
In recent years, the various kinds of display (image display) apparatuses or the like have been in a stage in which a display apparatus for executing signal processing for display driving by executing digital signal processing has come into wide use and has popularized.
Such a display apparatus operates to input/output a digital video signal, and a clock synchronized with the digital video signal in its inside through a data interface of a predetermined standard. The device inputted the digital video signal and the clock through the data interface, for example, executes necessary processing for the digital video signal in pixel unit at timing synchronous with the clock signal. Thus, the clock having a period corresponding to the pixel unit is also called a dot clock.
However, a frequency of the dot clock which is regulated by the data interface in the manner as described above does not necessarily become equal to that of the dot clock which is used in the pixel driving for the image display by the display device in the display apparatus. The reason for this is because the number of pixels (dots) in a horizontal direction (the number of horizontal pixels) which is determined in accordance with the dot clock or the like regulated in the data interface standard may be different from that which is constructionally set in the actual display panel. In other words, the number of horizontal pixels determined under the data interface standard is fixed as a certain number. On the other hand, the number of horizontal pixels of the display device becomes a number which, for example, should be changed in accordance with the screen size standard or the like. In such a manner, the number of horizontal pixels of the display panel has the variety. For this reason, the design idea for causing the number of horizontal pixels of the display panel to agree with that determined under the data interface standard is hardly adopted. In an actual case, the number of horizontal pixels of the digital video signal conforming to the data interface standard is converted into the number of horizontal pixels of the display device by executing processing called scaling. Also, the clock for display which is synchronized with the video signal in correspondence to the number of horizontal pixels obtained through this conversion is also generated by the scaling. The timing at which the pixels in the display device are driven is controlled in accordance with the clock for display. This leads to that the suitable display driving timing corresponding to the number of horizontal pixels of the display device is obtained. This technique, for example, is disclosed in Japanese Patent Laid-open No. Hei 11-202839.